47 lines
677 B
JavaScript
47 lines
677 B
JavaScript
'use strict';
|
|
const {Transform} = require('stream');
|
|
|
|
class ObjectTransform extends Transform {
|
|
constructor() {
|
|
super({
|
|
objectMode: true
|
|
});
|
|
}
|
|
}
|
|
|
|
class FilterStream extends ObjectTransform {
|
|
constructor(filter) {
|
|
super();
|
|
this._filter = filter;
|
|
}
|
|
|
|
_transform(data, encoding, callback) {
|
|
if (this._filter(data)) {
|
|
this.push(data);
|
|
}
|
|
|
|
callback();
|
|
}
|
|
}
|
|
|
|
class UniqueStream extends ObjectTransform {
|
|
constructor() {
|
|
super();
|
|
this._pushed = new Set();
|
|
}
|
|
|
|
_transform(data, encoding, callback) {
|
|
if (!this._pushed.has(data)) {
|
|
this.push(data);
|
|
this._pushed.add(data);
|
|
}
|
|
|
|
callback();
|
|
}
|
|
}
|
|
|
|
module.exports = {
|
|
FilterStream,
|
|
UniqueStream
|
|
};
|